Heating system for potable water and relatively small areas

ABSTRACT

A supplemental heating system for heating a first fluid such as potable water. The supplemental heating system is configured for use in a recreational vehicle having a primary heating system that also heats the first fluid. The supplemental heating system includes a heating element that heats a second fluid and a heat exchanging component removably fitted into the recreational vehicle and having a first fluid conduit for permitting the first fluid to enter and exit the heat exchanging component, and a second fluid conduit for permitting the second fluid to enter and exit the heat exchanging component. Heat from the second fluid is transferred to the first fluid within the heat exchanging component and thereby provides a heating operation of the first fluid independent of the heating system of the recreational vehicle.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional patent applicationSer. No. 60/087,184, filed May 29, 1998 and entitled POTABLE WATERHEATING SYSTEM. The subject matter of this application is incorporatedherein by this reference.

TECHNICAL FIELD

The present invention relates generally to heating systems, and moreparticularly, to potable water heating systems and heating systems foruse in recreational vehicles, campers, cabins, boats, and otherapplications with relatively small areas to be heated, as distinguishedfrom general residential home or commercial business/factory heatingapplications.

BACKGROUND ART

Conventional systems for heating water and/or relatively small livingspaces such as in a recreational vehicle generally fall into two classesof systems. The first class includes systems that have a heatingelement(s) that extend into a cavity which holds several gallons ofwater. That heating element ultimately heats the entire volume of water.Drawbacks to this first class include a lack of continuous hot water. Inother words, if the entire tank containing several gallons of water isused, there is no longer hot water for the user and a period of timemust elapse before hot water is available again. Because the entirevolume of water must be heated by the heating element, it takes arelatively long time period to heat the water with such a system.

The second class of systems involves heating a relatively small volumeof water with a gas or electric heating device. Conventional waterheating systems for recreational vehicles in this class usually includea propane or other open-flame “flash furnace” heating system thatdirectly heats the domestic eater. Open-flame systems like these arerelatively expensive and relatively unsafe when used in a recreationalvehicle. In addition, a propane heating system generally cannot providea constant supply of hot water. Furthermore, the heating device adds tothe complexity of the system and will wear and fail over time.

DISCLOSURE OF THE INVENTION

The present invention overcomes the drawbacks of conventional systems byproviding a water heating system/heating system that utilizes a flashheating process for heating potable water. The flash heating processincludes using water as the flash heating source. As a result, thepresent invention is capable of delivering a continuous supply of waterheated to a desired temperature such as between 100-130° F. for potablewater uses including drinking, washing, showering, bathing, etc. Thepresent invention is designed to be used in relatively small enclosures,such as for use in a space that is less than approximately 50,000 cubicfeet.

Preferably, the present invention is used to provide hot water, and alsoto provide heat to the coach of a recreational vehicle. The approximatevolume of space to be heated in a recreational vehicle coach isapproximately 25,000 cubic feet.

The invention may also be thought of as a water heating system for usein recreational vehicles such as boats and motor homes. The hot watersystem of the present invention uses fluid heated by an independent heatsource to heat domestic water.

These and other objects and advantages of the present invention will bemore readily understood after a consideration of the drawings and thedetailed description of the preferred embodiment which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a first embodiment of theinvention.

FIG. 2 is a schematic diagram of a heat exchanger used in the presentinvention.

FIG. 3 is a diagram showing how the second embodiment may be installedin a recreational vehicle.

FIG. 4 is a partially schematic and partially representational diagramshowing how the second embodiment of the invention may be installed in arecreational vehicle.

FIG. 5 is a side elevational view of a second embodiment of theinvention.

FIG. 6 is a schematic diagram of the second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT AND BEST MODE OFCARRYING OUT THE INVENTION

Referring to FIGS. 1 and 2, one version of the present invention (knowncommercially under the trademark CONSTAHOT™) is depicted as a heatingsystem for a recreational vehicle. The heating system includes a primarywater heater T with a primary water storage vessel, which may be a6-gallon tank. The heating system also includes a relatively smallpre-heater or heat exchanger X which is in communication with and isinstalled upstream of water heater T. The heat exchanger has a capacityto process and store about a quart of water, and may be thereforethought of as a secondary water storage vessel.

Heating fluid from an independent heat source, such as a combustionengine or furnace marketed under the trademark HURRICANE, enters andexits water heater T at H1 and H2, respectively. The heating fluid movesthrough a pipe to the input H3 of heat exchanger X and exits the heatexchanger at H4. The heating fluid is maintained in a conduit C1 betweeninput H3 and output H4 FIG. 2). The conduit directs the heating fluidthrough first stacked stainless steel plates P1 inside heat exchange X.The independent heat source thus provides heating fluid to both waterheater T and heat exchanger X. However, it is within the scope of theinvention for the independent heat source to supply only heat exchangerX with heating fluid. The heat source is preferably a 12volt/diesel-fired hydronic heat source with a 40,000 BTU output. Theheating fluid is preferably a two-part mixture of glycol and water. Apreferred range for that mixture is between 30-50% glycol and acorresponding 70-50% of water. It has been found that a 40% glycol/60%water mixture is optimal for the recreational vehicle application of thepresent invention.

Still referring to FIG. 1, the water to be heated, known as domestic orpotable water, enters the invention at W1. The domestic water entersheat exchanger X at W2 and is pre-heated by the heating fluid by flowingthrough a conduit C2, which directs the domestic water through secondstacked stainless steel plate-like elements P2, which alternate withfirst stacked elements P2 as shown in FIG. 2, to allow heat to transferbetween the two flows. The domestic water exits the heat exchanger at W3and enters water heater T at W4. The domestic water interacts with theheating fluid within the water heater by conventional heat transfermethods and exits the water heater at W5. A tempering valve V allows auser to adjust final water output temperature. If domestic water at W5is too hot, tempering valve V is adjusted to mix cooler water from W1 tolower the temperature of the water. Water at the desired temperatureexits the invention at W6 ready to use.

FIG. 2, is a schematic depiction of how heated water is used to heatdomestic (cold) potable water in a heat exchanger. It should beunderstood that various heat exchangers may be used depending upon theapplication and government regulatory requirements. Heat exchangers thatare double-walled with a vented air gap between the double walls may bepreferred to meet government safety requirements. One such double walledheat exchanger is made by Doucette Industries, Inc. and given part no.NSY2M1/1P-7SCC (O) SM.

A variation of the above embodiment adds a sensing switch (not shown)that senses the temperature of the domestic water in the 6-gallon tank.When the temperature reaches a certain level, the independent heatsource is activated, thereby circulating heating fluid through the heatexchanger and pre-heating the domestic water.

FIG. 3 provides an illustration of a typical plumbing system for arecreational vehicle that includes the CONSTAHOT™ version of theinvention. Water in an expansion tank 10 is drawn by a pump 12 into afurnace or independent heat source 14. After passing through heatexchange X and water heater T, the water flows through an exchanger 16that transfers heat from the engine 18 of the recreational vehicle. thewater then travels to various fan units 20 where the heated watertransfers heat to the interior of the recreational vehicle. The specificpath the water travels is determined by the states of a summer valve 22and a winter valve 24, which are alternatively opened and closed. Whensummer valve 22 is open and winter valve 24 is closed, water bypassesfan units 20 and returns to expansion tank 10. When summer valve 22 isclosed and winter valve is open, water flows through fan units 20 toheat the interior of the vehicle.

FIG. 4 shows a partially schematic/partially representational depictionof another plumbing system that includes the CONSTAHOT™ version of theinvention, and also illustrates how and where that version of theinvention may be located in a standard coach of a recreational vehicle.Recreational vehicle RV includes a living area 30, a kitchen 32, abathroom 34, and a bedroom 36. Water flows from expansion tank 10,through pump 12, and into a furnace or independent heat source 14. Thewater is heated by exchanger 16 and then flows through either a summervalve 22 or winter valve 24. If the water flows through summer valve 22,the water returns to expansion tank 12. If the water flows throughwinter valve 24, the water goes through fan 20 a in living area 30 andthen through the CONSTAHOT™ system CH. The water flows through fans 20and returns to expansion tank 10.

FIGS. 5 and 6 show another embodiment of the invention, also referred toas the MAGICHOT™ heating system, which is a supplemental heating systemthat includes a heat exchanging component such as heat exchanger X, thatcan be associated with or fitted onto an existing primary heating systemsuch as a water heater unit B. Heat exchanger X is retrofittable orremovably fitted into a recreational vehicle. Heating fluid from aheating element such as an independent heat source A enters the heatexchanger at H1, flows through a conduit C3 within/the heat exchanger,and exits the heat exchanger at H2. A fluid such as domestic or potablewater enters at D1, flows through tempering valve V, and enters the heatexchanger at D2. The domestic water flows through a conduit C4 in theheat exchanger and exits the heat exchanger at D3. As in the embodimentshown in FIG. 1, tempering valve V moderates the temperature of theoutput domestic water by mixing it with unheated domestic water from D1.A sensing switch (not shown) can also be provided in the existing waterheater to activate the independent heat source to begin the pre-heatingprocess.

Another way to describe the invention is as follows: FIGS. 1 and 2disclose the CONSTAHOT™ embodiment of the invention, which combines areplacement 6-gallon domestic hot water tank with a high efficiency,extremely compact heat exchanger that, in conjunction with the HURRICANEFURNACE, will provide 106 degree hot water for as long as is desired.The system typically requires a heat source with a minimum of 36K BTU.The CONSTAHOT™ has a sensing switch that, when the water temperature inthe 6 gallon buffer tank reaches a certain level, signals the Hurricanefurnace to come on, circulating hot fluid through the CONSTAHOT™ heatexchanger and pre-heating the domestic water. The CONSTAHOT™ uses astandard UL listed hot water heater made by Seaward Products which has a1500 W 120 V electric element as well as a small heat exchange loop. Thepre-heating heat exchanger is IAMPMO rated for domestic water. FIGS. 5and 6 disclose the MAGICHOT™ embodiment of the invention, which is is anadd-on accessory for installations where the replacement of the entirewater heater is not desirable. It consists of the same pre-heating heatexchanger that is used with the previous embodiment and is containedthat is used with the previous embodiment and is contained in a small,easily mounted box with clearly labeled hose connections. An accessorykit consisting of a sensing trigger and pipe fittings is available toallow conversion of most existing hot water heaters. Both the CONSTAHOT™and the MAGICHOT™ are compact, easily installed units that add anunlimited hot water feature to systems where, because of space, fuel orsafety considerations, such a feature was unavailable.

The following Table provides technical information that may be helpfulin constructing the invention.

TABLE ConstaHot MagicHot Size: 14″W-15″H-21″D 9″W-5″H-4.5″D Fittings: Onleft side, 2 ⅝ hose barbs On front, 2 ⅝ hose barbs 2 ½ pipe male pipe 2½ male pipe fittings. fittings. El. No el. Storage: 6 gallons inaluminum tank N/A BTU Req.: Minimum 36K Minimum 36K Construction: CaseSS, Plumbing Copper/ Case AL, Plumbing Brass Copper/Brass Temp. Valve:Watts 70-A 120-160 Watts 70-A 120-160 degrees Adj degrees Adj.

Another embodiment of the invention, known under the trademarkCOMFORTHOT™, is a supplemental space heating system that includes asupplemental heating unit coupled to an existing hot water heatingsystem in a recreational vehicle, and is powered by electrical powerfrom a conventional AC power outlet. Preferably, the existing hot waterheating system used with this embodiment is the first embodiment of thepresent invention as described above and shown in FIGS. 1 and 2. Thesupplemental heating unit includes a tank enclosed by an outer covering.Cold water is input at the bottom of the tank, heated by a pair of2000-Watt heating elements, and allowed to exit the invention. Aplurality of thermostats control the actuation of the unit.

This embodiment of the invention is designed to be installed in a closedcircuit relationship with the currently existing furnace and holdingtank of a recreational vehicle. Water from the tank is driven by a pumpthrough a furnace, through a series of heat exchangers and back into theinvention. This embodiment may be wired via a three-way switch to anexternal source of 120 Volt AC power, in parallel with an airconditioner mounted on the recreational vehicle. This embodiment isadvantageous because an external source of power can be used to heatwater instead of using a conventional diesel fired furnace. This isimportant because a recreational vehicle can take advantage of anelectrical power hookup at an RV park, where the cost of operating theinvention is absorbed into the overall nightly rental fee that ischarged by the RV park. Another advantage of this embodiment is that itis a self-contained unit, and is compact and easy to install. Yetanother advantage is that the invention uses the existing electricalcircuitry that is designed for use for the air conditioner in arecreational vehicle. Still another advantage is that the tank of thepresent invention provides additional fluid capacity in the waterheating system of a recreational vehicle. Still another advantage isthat the invention can be used as a sole heating source for arecreational vehicle as well as a supplement to an existing dieselpowered furnace.

One advantage of all embodiments of the invention is that they can beused with a pre-existing, independent heat source. This is importantwhen the invention is installed in an environment where weight and spaceis at a premium, such as in a boat, camper, trailer or otherrecreational vehicle. Another advantage of the invention is that thepre-heating operation that takes place in the heat exchanger rapidlyheats a small amount of water that is immediately available for use.Additionally, the flash heating process introduces no additional movingparts to the overall heating system, and is safer than openflame/gas/electric heaters because those heaters present a potentialfire hazard.

The invention may be thought of as the devices or systems shown above.It may also be thought of as a method of using a water-containing fluidas a flash heating source. It may also be thought of as a water-to-watermethod of heating potable water. Distinguishing features of theinvention include: (1) flash heating a water-containing fluid to heatpotable water; (2) using a glycol/water mixture as a heating fluid, aspreviously described; (3) providing water-to-water heating of potablewater; (4) providing a heating system with a continuous hot-wateroutput; (5) providing a heating system with no moving parts; (6)providing a non-demand system; and (7) providing a water heating systemthat slaves off of an existing water heater.

While the present invention has been shown and described with referenceto the foregoing operational principles and preferred embodiment, itwill be apparent to those skilled in the art that other changes in formand detail may be made therein without departing from the spirit andscope of the invention as defined in the appended claims.

I claim:
 1. A supplemental heating system for heating a first liquid,the supplemental heating system being configured for use in arecreational vehicle, the recreational vehicle having a primary heatingsystem that also heats the first liquid, the supplemental heating systemcomprising: a heating element that heats a second liquid; and a heatexchanging component removably fitted into the recreational vehicle andhaving a first liquid conduit for permitting the first liquid to enterand exit the heat exchanging component, and a second liquid conduit forpermitting the second liquid to enter and exit the heat exchangingcomponent; wherein heat from the second liquid is transferred to thefirst liquid within the heat exchanging component to provide a heatingoperation of the first liquid independent of the primary heating systemof the recreational vehicle.
 2. The supplemental heating system of claim1, wherein the supplemental heating system heats the first liquid priorto the primary heating system heating the first liquid.
 3. Asupplemental potable water heater for a recreational vehicle, thevehicle having a primary potable water heating system installed thereinthat heats potable water, the supplemental potable water heatercomprising: a supplemental heating element independent of the primarypotable water heating system; and a heat exchanging component thattransfers heat generated by the supplemental heating element to thepotable water prior to the potable water being heated by the primarypotable water heating system, thereby tending to provide a substantiallyconstant flow of potable water at a predetermined temperature.
 4. Thesupplemental potable water heater of claim 3, further including: aheating fluid that transfers heat from the supplemental heating elementto the potable water; a first conduit that directs the potable waterinto and out of the heat exchanging component; and a second conduit thatdirects the heating fluid into and out of the heat exchanging component.5. The supplemental potable water heater of claim 4, further comprisinga tempering valve configured to mix selectively the potable waterflowing into the first conduit with the potable water flowing from thefirst conduit, thereby to vary the temperature of the potable waterflowing from the first conduit.
 6. The supplemental water heater ofclaim 3, wherein the supplemental potable water heater is retrofittableinto the recreational vehicle.
 7. A heating system for a recreationalvehicle, comprising: a primary water heater located in the recreationalvehicle; a primary water storage vessel associated with the primarywater heater; a pre-heater in communication with and installed upstreamof the primary water heater, the pre-heater including a supplementalheat source independent of the primary water heater; and a secondarywater storage vessel associated with the pre-heater, the secondary waterstorage vessel having a substantially smaller water volume storagecapacity than that of the primary water storage vessel; wherein thepre-heater heats water prior to the water being heated by the primaryheater, thereby tending to provide a substantially constant flow ofwater at a preselected temperature.
 8. The heating system of claim 7,further including: a heating fluid that transfers heat from thepre-heater to the water; a first conduit that directs the water into andout of the pre-heater; and a second conduit that directs the heatingfluid into and out of the pre-heater.
 9. The heating system of claim 8,further comprising a tempering valve that is configured to mixselectively the water flowing into the first conduit with the waterflowing out of the first conduit to vary the temperature of the waterflowing out of the first conduit.
 10. The heating system of claim 7,wherein the pre-heater is powered independent of the primary heatingsystem and the recreational vehicle.
 11. A supplemental heating systemfor heating a first fluid, the supplemental heating system beingconfigured for use in a recreational vehicle, the recreational vehiclehaving a primary heating system that also heats the first fluid, thesupplemental heating system comprising: a supplemental heating elementindependent from the primary heating system that heats a second fluid;and a heat exchanging component removably fitted into the recreationalvehicle and having a first fluid conduit for permitting the first fluidto enter and exit the heat exchanging component, and a second fluidconduit for permitting the second fluid to enter and exit the heatexchanging component; wherein heat from the second fluid is transferredto the first fluid within the heat exchanging component to provide aheating operation of the first fluid independent of the primary heatingsystem of the recreational vehicle.
 12. The supplemental heating systemof claim 1, wherein the supplemental heating system heats the firstfluid prior to the primary heating system heating the first fluid.